Panasonic NN-GS597M, Service Manual

Page: 20 / 38

WARNING
1. High voltage is present at the output terminals of the High Voltage
Inverter (U) including aluminum heat sink during any cook cycle.
2. It is neither necessary nor advisable to attempt measurement of the
high voltage.
3. Before touching any oven components, or wiring, always unplug
the power cord and discharge the high voltage capacitors.
7.1. Primary latch switch
Secondary Latch switch and
power relay RY3
1. Unplug lead connectors to Power Relay RY3 and verify
open circuit of the Power Relay RY3 (1-2) terminals.
2. Unplug lead connectors to Primary Latch Switch and
Secondary Latch Switch.
3. Test the continuity of switches at door opened and closed
positions with ohm meter (low scale).
Normal continuity readings should be as follows.
Door Closed Door Opened
Primary Latch Switch 0
Ω
(Close)
Ω
(Open)
Secondary Latch Switch 0 Ω (Close) Ω (Open)
Power Relay RY3 Ω (Open) Ω (Open)
7.2. Short switch & monitor
1. Unplug lead wires from Inverter Power Supply (U) primary
terminals.
2. Connect test probes of ohm meter to the disconnected
leads that were connected to Inverter Power Supply (U).
3. Test the continuity of short switch with door opened and
closed positions using lowest scale of the ohm meter.
Normal continuity readings should be as follows.
Door Opened Door Closed
0
Ω
(Close)
Ω
(Open)
7.3. Magnetron
Continuity checks can only indicate an open filament or a
shorted magnetron. To diagnose for an open filament or
shorted magnetron.
1. Isolate magnetron from the circuit by disconnecting the
leads.
2. A continuity check across magnetron filament terminals
should indicate one ohm or less.
3. A continuity check between each filament terminal and
magnetron case should read open.
7.4. Membrane key board
(Membrane switch assembly)
Check continuity between switch terminals, by tapping an
appropriate pad on the key board. The contacts assignment of
the respective pads on the key board is as shown in digital
programmer circuit.
7 COMPONENT TEST PROCEDURE
20
NN-GS597M